The present invention relates to a device for locking the beads of a tire against flanges of a multi-piece rim, which device is intended to improve low-pressure travel performance. The multi-piece rim has at least one removable flange or is either a two-part rim or a multiple-sector rim.
For certain travel it is necessary to reduce the inflation pressure of the tires considerably. This is true on soft, marshy or sandy ground. In this case, the beads are insufficiently locked on their seats. There is a danger of the loosening of one or both beads, which suddenly leave the flange of the rim and move axially towards the inside of the rim. In the case of tire/rim assemblies wherein the tire is mounted on the rim without an independent inner tube, this results in a sudden loss of residual pressure and an instantaneous flattening of the tubeless tire. In the case of tire/rim assemblies wherein the tire is mounted on the rim with an inner tube, such displacements of the beads are also intolerable, because they result in rapid deterioration of the inner tube. Mention may also be made of another drawback found in such low-pressure travel, namely the accidental loss of drive due to the turning of the tire on its rim, which may furthermore also lead to a flattening of the tire.
In order to overcome these drawbacks, the idea has been proposed heretofore of mounting on the rim, between the beads, a ring which prevents the beads from moving towards each other. However, in order to be effective such rings must be rigid; in general, they are formed of rubber of very great hardness, possibly reinforced with cores or cables. European patent application No. 0,084,490 describes one such device which is formed of a ring containing a reinforcement. French patent No. 1,173,895 discloses another embodiment of a bead retention ring designed specifically for rims with a removable flange. Such rings must be introduced into the tire between the beads before mounting the assembly on the rim, which is difficult since these rings are heavy, bulky and very inflexible.